Composites are a combination of materials differing in composition and/or form to obtain specific characteristics and properties. The constituent materials substantially retain their identities. One type of composite material is a ceramic matrix composite (CMC). A CMC can have a matrix made of a ceramic material and reinforcing fibers made of the same or a different material.
Composite components are difficult to inspect using traditional non-destructive methods, such as thermal, x-ray and ultrasound imaging. While these methods are well suited for materials with distinct differences in some material property, they are not sensitive enough to adequately inspect the features of interest of a composite component. In some cases, the constituent materials of a composite can be identical or substantially identical. For example, an alumina-alumina CMC includes alumina reinforcing fibers in an alumina matrix. Such a material is not amenable to conventional non-destructive inspection methods. Further, composite materials are inherently porous, and they can contain natural air voids. However, one common source of material defects in a composite material is trapped air. Under conventional inspection methods, it is difficult to consistently distinguish unwanted air pockets from natural voids. Thus, there is a need for a system that facilitates the non-destructive inspection and evaluation of composite components.